The researchers modified the M13 virus, which infects only bacteria, to grow proteins on its surface that attract amorphous iron phosphate.

The result: Wires just nanometers thick of the material, which is cheaper and environmentally friendlier than ones currently used to make electrodes for lithium-ion batteries.

The scientists also programmed the virus so that one end became sticky to carbon nanotubes, which are extraordinarily good conductors of electricity.

Electrons easily travel along the carbon nanotubes to the amorphous iron phosphate networks, transferring energy in a very short time.

Using these ingredients, the researchers devised coin-sized batteries comparable in performance to commercial lithium-ion batteries.

"The more genetic engineering we did, the better it got," said researcher Angela Belcher, a materials scientist at the Massachusetts Institute of Technology.

Carbon nanotubes are still expensive, and researchers debate what risks they might pose to the environment. If the nanotubes become a barrier, the same process could be performed with other good electrical conductors such as silver or gold, Belcher said.

While her team is still in the early stages of its work, Belcher thinks the project could soon get "twice the power performance of what we demonstrated with this proof of principle here."